TemaNord 2006:594
Handling and assessment of
leachates from municipal
solid waste landfills in the
Nordic countries
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Nordic Council of Ministers Nordic Council
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Content
Content ... 5 Preface... 7 Summary ... 9 Sammendrag... 13 Objective ... 17 1. Background ... 19 1.1 Chemicals of concern ... 19 1.2 Leachate monitoring... 201.3 Environmental effects of leachate ... 21
1.4 Degree of stabilisation/maturation (Final Storage Quality) ... 22
2. Sampling Guidelines/Programmes ... 29 2.1 Denmark... 29 2.2 Finland ... 30 2.3 Iceland ... 31 2.4 Norway... 33 2.5 Sweden ... 34
2.6 Examples of leachate reporting in some EU countries ... 34
2.7 Differences in limit values... 35
3. Existing Leachate Data – National Levels... 37
3.1 Denmark... 37 3.2 Finland ... 38 3.2.1 Toxicity ... 39 3.3 Iceland ... 40 3.4 Norway... 41 3.5 Sweden ... 43
4. Existing Leachate Data – Discussion... 45
4.1 Trends in leachate Concentrations... 45
4.2 Leachate Concentrations ... 45
5. Gaps in Leachate Data ... 49
5.1 General ... 49 5.2 Finland ... 49 5.3 Iceland ... 50 5.4 Norway... 50 5.5 Sweden ... 50 6. Guideline Recommendations... 51 6.1 Denmark... 51 6.2 Finland ... 51 6.3 Iceland ... 52 6.4 Norway... 52 6.5 Sweden ... 52
6.6 Suggestion for a common minimum requirement for leachate monitoring ... 53
7. References ... 55
8. List of Annexes... 57
Annex A 1. Leachate monitoring results from Denmark ... 59
Annex B.1. Monitoring results from Finland... 73
Annex C.1. Leachate monitoring results from Iceland ... 77
Annex D.1. Leachate monitoring results from Norway. ... 79
Annex D.2. OBS-listen... 93
Annex D.3. Chemicals with priority: significant reduction within 2000 and complete halt within 2005... 97
Annex D.5. Monitoring programme for environmental risk assessment of landfills... 103
Annex D.6. Sampling guidelines... 107
Annex E.1. Leachate monitoring results from Sweden. ... 135
Annex F.1. Summary of leachate monitoring data from the Nordic countries. ... 139
Annex F.2. Comparison of limit values ... 163
Annex G.1. ... 165
Annex G.2. ... 167
Annex G.3. ... 169
Preface
This project was initiated by the Nordic Council in 2003. It is a collabora-tion with consultants from Denmark, Finland, Iceland, Norway and Swe-den. Norway and Iceland have edited the report, but the consultant group is responsible for the content. Each consultant is responsible for the sub-mission of the national data and presentation.
Summary
EU-legislation, in particular the Landfill Directive, requires environ-mental monitoring of landfills, both pre- and post closure. The content of the guidelines of the Nordic countries that are brought together in this report are based on the requirements given in European legislation. Thus, the guidelines in this report are relevant for landfills subject to EU legis-lation.
Current leachate monitoring guidelines and practices differ among the Nordic countries. The differences are mainly based on different interpre-tations by the Nordic countries of the requirements in the Landfill Direc-tive, resulting in differences in national policies. Also, economic and environmental considerations may be differently emphasised. Thus, exist-ing guidelines are often built on a country specific trade-off between European legislation, scientific and environmental risks and socioeco-nomic considerations. In Denmark the parameters given in the EC Direc-tive are to be supplemented by organic parameters such as BTEX, PAH, PCB and mineral oil. Norway has new guidelines on both diffuse and point source emissions of leachate. The guidelines reflect the Norwegian list of priority hazardous substances and contain more parameters than those included in the EC Council Decision on waste acceptance criteria.
In this report a comparison is given on national leachate monitoring guidelines that were described by the consultants of Norway, Finland, Denmark, Sweden and Iceland. Based on the information that was given by these consultants suggestions for a minimum requirement monitoring program are given. This project has identified a lack of knowledge on a number of parameters in leachate monitoring within the Nordic countries, getting this knowledge might be considered to give a better understanding of possible impacts of leachate released from landfills into the environ-ment. (or landfill leachate emitted into the environment).
From the existing leachate data that the participating countries submit-ted the following can be summarized:
Denmark has no national collection of leachate data, monitoring is or-ganized at a County level, in various ways. The presented leachate data represent a limited number of landfills, mainly with mineral wastes such as ash, but also other wastes.
Finland has no target values on leachate emissions to wastewater treatment plants. Leachates are generally evaluated on quantity, COD, BOD, NH4-N and heavy metals. Data are presented from 45 landfills that were operational until 1987 and 2 landfills that have been operational after 1987. The data show that organic matter in leachate in Finland is comparable to that in domestic wastewater , but leachate is higher in N.
Cl levels in leachate are high enough to cause corrosion. The content of heavy metals in leachate is generally low. The most prevailing organic pollutants are PAH and phthalates. The leachate shows some toxicity, both measured with daphnia and algae.
In Iceland time series of leachate data exists on a national level, but vary in frequency and the number of parameters that are monitored per landfill, as bigger landfills are monitored more extensively than smaller ones. Only non-hazardous and inert waste is landfilled, but a landfill for hazardous waste is under construction.
Leachates from Norwegian landfills are being monitored, with a wider spectrum of substances than in most other nordic countries, following an update of regulations in 2005. The current Norwegian leachate data show that concentrations in leachate are significantly higher compared to do-mestic wastewater. This is particularly the case for concentrations of COD and some heavy metals (Cd, Cr and Pb), both as mean tion (1 to 5 times), but even more pronounced for maximum concentra-tions ( > 10 times), especially in periods when there is relatively little precipitation and subsequently the leachate flow relatively concentrated. Studies on diffuse emissions from landfills show that the threshold values are exceeded to a large degree when evaluated according to general pa-rameters (8 to 286 times), less by heavy metals (2 to 80 times) and least by organic pollutants (1 to 10 times). In leachate sediments the parame-ters measured above the threshold limits were phenols, PAH and tin or-ganic compounds.
In Sweden leachate characteristics have been studied in several re-search projects and control programs, including more than 400 parame-ters from 30 sites. The leachate showed both estrogenic and androgenic activities. More than 8 million m3 of leachate was collected in 2003, of which 5 million m3 was treated in municipal wastewater treatment plants. The number of active landfills was 192 in 2003, expected to decline to 100 by 2008.
It is difficult to compare the reported leachate data from the different nordic countries, because of the differences in collection routines, site specific conditions, waste sorts landfilled and other factors. Denmark has presented more data on mineral waste, including ash from incineration plants, compared to the other countries. These data might represent future leachate quality if incineration of waste is going to be more important. The leachate quality reported from Denmark show relatively high con-centrations, surprisingly also for COD and nitrogen. When nordic leachate quality are compared within the Nordic countries, there seem to be relative small differences, except high maximum values for Fe and Zn in Norway. Finland reports higher levels for Zn.
Based on this study, the following guideline recommendations can be made for the Nordic countries:
Handling and assessment of leachates from municipal solid waste landfills 11
Denmark: a fixed system for sampling frequency is suggested, with the Counties defining the sampling parameters applicable locally.
Finland; all leachate should be collected and treated.
Iceland mentions locally adaptation of monitoring programs and flow-based evaluation of the emissions.
Norway: hydraulically based monitoring is suggested as well as specific guidelines on sampling and analysis and monitoring of acute and chroni-cally toxicity of leachate. Emissions to the atmosphere should also be included in the monitoring, and also time or weight specific threshold values of emissions.
An overall conclusion might be that although the Nordic countries are subject to the same EU-legislation on waste treatment and leachate, both the reported experiences and the present guidelines on leachate collec-tion, monitoring and analysis differ to a relatively large extent. Regions might benefit from a stronger consensus on leachate control, both on a national and Nordic level. Recommendations and a suggestion for a minimum level of leachate monitoring is given in chapter 7.
Sammendrag
EUs lovgivning, og i særdeleshet Deponidirektivet, foreskriver miljørettet monitorering av deponier, både i drifts- og i etterdriftsfasen. De nordiske retningslinjer og veiledere som er gjengitt her er basert på krav gitt i EUs lovgivning, og er dermed relevante for deponier underlagt denne lovgiv-ning.
Nåværende retningslinjer og praksis for monitorering av sigevann er ulike i de nordiske landene. Forskjellene er i hovedsak basert på ulik for-ståelse av krav gitt i Deponidirektivet og som har gitt ulike nasjonale fremgangsmåter. I tillegg kan økonomiske og miljømessige forhold vekt-legges ulikt. Dermed vil eksisterende retningslinjer ofte bestå av en ba-lanse mellom europeisk lovgivning, vitenskapelig og miljømessig risiko og sosioøkonomiske vurderinger. I Danmark er parametrene som er gitt i EUs deponidirektiv supplert med organiske parameter som BTEX, PAH, PCB og mineralolje. I Norge er det gitt ut nye retningslinjer både når det gjelder diffuse utslipp og punktutslipp. Retningslinjene reflekterer den norske listen over prioriterte miljøgifter og omfatter flere parametre enn de som er inkludert i EUs direktiv over karakterisering av avfall.
I denne rapporten er det gitt en sammenligning mellom nasjonale ret-ningslinjer for overvåking av sigevann, som beskrevet av konsulenter fra Danmark, Finland, Island, Norge og Sverige. Et minimumsnivå for over-våking av sigevann er gitt, basert på informasjon gitt av de ulike konsu-lentene. Prosjektet har identifisert kunnskapshull når det gjelder en rekke parametre innen sigevannsmonitorering i de nordiske landene, som kan gi mangelfull håndtering av de effekter som utslipp av sigevann fra deponier kan gi i miljøet.
I det følgende er det gitt sammendrag angående eksisterende sige-vannsdata i de deltagende landene:
Danmark har ingen nasjonal innsamling av sigevannsdata. Overvåking er organisert av de ulike amter, på ulike måter. De data som presenteres representerer et begrenset antall deponier, mange med mineralsk avfall som f.eks. aske, men også andre avfallstyper.
Finland har ingen terskelverdier når det gjelder påslipp av sigevann til renseanlegg for avløpsvann. Sigevann blir generelt vurdert mht. mengde, KOF, BOF, NH4-N og tungmetaller. Data er presentert for 45 deponier, som var i drift inntil 1987, og 2 deponier som er i drift etter 1987. Datae-ne viser at organisk stoff i sigevann i Finland er sammenlignbart med avløpsvann fra husholdninger, men inneholder mer N. Innholdet av Cl er tilstrekkelig til å gi problemer med korrosjon. Innholdet av tungmetaller er generelt lavt. De organiske miljøgifter som forekommer hyppigst er
PAH og ftalalter. Sigevannet er noe toksisk, både målt med daphnia og alger.
Island har tidsserier på sigevannsdata på nasjonalt nivå, men antall pa-rametre og frekvensen av målingene varierer siden store deponi måles hyppigere enn små. Kun ordinært og inert avfall blir deponert, men et deponi for farlig avfall er under bygging.
Sigevann fra norske deponi blir overvåket med et bredere spekter av stoffer enn de fleste av de øvrige nordiske landene, etter en oppdatert veileder fra 2005. Eksisterende sigevannsdata viser at konsentrasjonene er betydelig høyere enn i avløpsvann. Dette gjelder særlig for KOF og enkelte tungmetaller (Cd, Cr og Pb), både som middelverdi (1 til 5 ganger høyere), og særlig som maksimumsverdi (> 10 ganger høyere), særlig i perioder med lite nedbør og lav sigevannsproduksjon. Studier av diffuse utslipp fra deponier viser at eksisterende terskelverdier overskrides i høy grad både målt som generelle parametre (8 til 286 ganger), i noe mindre grad for tungmetaller (2 til 80 ganger), og i mindre grad for organiske forbindelser (1 til 10 ganger). Parametre som overskrider terskelverdier i sigevannssediment var fenoler, PAH og tinorganiske forbindelser.
Karakterisering av sigevann i Sverige er beskrevet i flere forsknings-prosjekter og kontrollprogram, og har inkludert mer enn 400 parametre fra 30 lokaliteter. Sigevannet viste både østrogen- og androgenaktivitet. Mer enn 8 millioner m3 av sigevann ble innsamlet i 2003, hvorav 5 milli-on m3 ble behandlet i renseanlegg for sigevann. Antall aktive deponier var 192 i 2003 og forventes å avta til 100 innen 2008.
Det er vanskelig å sammenligne eksisterende sigevannsdata fra de nordiske landene, fordi ulike rutiner i innsamling, stedsspesifikke ulikhe-ter, ulike avfallstyper og andre faktorer varierer. Danmark har presentert mer data på mineralske avfallstyper, f.eks. aske fra forbrenningsanlegg, sammenlignet med de øvrige landene. Disse data kan representere forven-tet sigevannskvaliforven-tet i fremtiden siden avfallsforbrenning forventes å bli viktigere.
Sigevannskvaliteten rapportert fra Danmark viste relativt høye kon-sentrasjoner, overraskende nok også for KOF og nitrogen. Når sige-vannskvaliteten sammenlignes innen de nordiske landene ser det ut til å være små forskjeller, kanskje med unntak av høye konsentrasjoner for Fe og Zn i Norge, og høye verdier for Zn i Finland.
Følgende forslag til retningslinjer for overvåking av sigevann er frem-kommet i dette prosjektet:
Danmark: et system for innsamlingsfrekvens er foreslått, mens de ulike amter definerer parametre med lokal tilpasning.
Handling and assessment of leachates from municipal solid waste landfills 15
Island: lokal tilpasning av monitoreringsprogram og mengdebasert evalu-ering av utslippene.
En overordnet konklusjon fra prosjektet er at til tross for at de nordiske landene er underlagt felles EU-lovgivning når det gjelder avfalls- og si-gevannsbehandling, er det relativt store forskjeller i eksisterende veilede-re og veilede-retningslinjer for sigevannsinnsamling, prøvetaking og analyse. Regioner innen de nordiske land kan dra fordel av en større consensus når det gjelder kontroll av sigevannet. Anbefalinger og forslag til et mini-mumsprogram for sigevannsovervåking er gitt i kapittel 7.
Objective
The main objective of this project is to summarise national guidelines and give recommendations for leachate monitoring in the Nordic countries, based on today’s knowledge of leachate quality and quantity in these countries.
Final milestone:
The aim is to give recommendations to the Nordic countries on how to fulfil the requirements for leachate monitoring that are based on the Landfill Directive. The recommendations must include suggestions of suitable leachate parameters. Leachate parameters might give an indica-tion for the degree of stabilisaindica-tion of a landfill, i.e. the progression to final storage quality, and thus assist with estimating the necessary length of the aftercare period.
Further recommendations will be given on how to evaluate environ-mental impacts from leachate analysis. These recommendations will be given in the view of obligations from international conventions (such as the Stockholm-convention). Lastly, recommendations are given for pos-sible further investigations and research concerning environmental im-pacts of discharge of leachate into the environment, that might be helpful to reach a more consistent approach of leachate monitoring and treatment within the nordic countries.
1. Background
The extent of environmental effects of the release of municipal solid waste (MSW) leachate into the environment is still under debate. Envi-ronmental impact assessments on the discharge of landfill leachates into the environment are often unsatisfactory because of the focus on a limited number of factors and substances, usually nutrients and metals. Little is known about the abundance and possibly environmental impacts of or-ganic pollutants such as the PCB (polychlorinated biphenyl), DDT (di-chlorodiphenyltrichloroethane), and brominated flame retardants, chlo-rinated solvents, phenols and phthalates, hormonally active agents (HAA’s), pharmaceuticals and others in leachate. A number of studies and reports have shown presence of these substances. Logically, landfills are suspected to contain most of the substances that are produced and used in our society, but little is known about their concentrations in leachate, degradation, mobilisation and possible (co-)effects in ground- and surface waters and surrounding ecosystems.
The Landfill Directive (1999/31/EC) stipulates that leachate from landfills must be collected and treated to the “appropriate (national) standard” that is required for their discharge. Typically, this means leachate from landfills for non-hazardous and hazardous waste. An ap-propriate standard remains to be defined, and depends today in most cases on local evaluation. There are also requirements to control water from precipitation, surface water and groundwater entering into the land-fill body. Furthermore, the Directive stipulates that control and monitor-ing systems should reflect the characteristics of the landfilled waste.
It is assumed that the Nordic countries generate similar waste types, and have comparable techniques of landfilling. Climatic conditions are relatively similar with cold and cold temperate climates including dry winter seasons and periods with snow-melting or heavy precipitation. Many recipients are sensitive for surges of water pollution.
An important aspect of monitoring landfills is to identify when a site no longer presents a significant risk of pollution or harm to human health or the environment, which indicates that it is stabilized.
1.1 Chemicals of concern
The European environmental authorities operate with lists of priority chemicals of particular environmental concern, see Table 1.
Table 1. Examples of lists of hazardous chemicals
Name No. of chemicals Reference
Denmark Max. C of substances in groundwater
26 Statutory order of
landfills
Norway The Observation List >250 White paper no. 58, 1996–1997
(See Annex D.2 to this report)
Norway List of Priority Sub-stances
33 White paper no. 58
2002–2003
(Annex D.3)
Norway Guidelines on leachate monitoring
Leachate: 24 Screening: 17 Sediments:15
SFT guideline no. TA– 2077/2005 (Annex D.4)
Norway Guidelines on risk assessment of landfills
Leachate: 42 Sediment: 28
SFT guideline no. TA– 1995/2003
(Annex D.5)
Finland List of major contami-nants for which permit values are set
12 groups of sub-stances
National Regulation 169/2000 (Water Framework Directive 2000/60/EC, list VIII)
Germany Requirements for
leachate emissions
17 Annex G.2
EU Pollution Inventory 91 Council Directive
1996/61/EC
(Annex G.1)
EU Leachate limit values for inert waste and hazardous waste going to landfill
17 Council Decision
2003/33/EC
For Norway: The Observation List includes chemicals with particular risk to human health and the environment and is a part of the national regula-tion on classificaregula-tion and labelling of hazardous chemicals. The Priority List includes chemicals of concern because of their toxicity, mobility and availability.
1.2 Leachate monitoring
Leachate monitoring programmes may vary according to landfill category (type of waste, capacity), and whether the landfill is operational or closed. In addition to a basic programme, landfills are required to carry out extended monitoring programmes. Common reporting practices are to evaluate contents of organic matter, nutrients and toxicants leachate, rela-tive to total emission limit values that can both be recipient independent or -dependent.
In some countries only a few of the listed substances causing concern are regularly monitored in municipal solid waste (MSW) leachate, al-though most of them are fairly common in many types of waste. In this report, many of the substances that are mentioned in the list above have not been monitored until now but should be monitored according to cur-rent (EU)legislation.
Handling and assessment of leachates from municipal solid waste landfills 21
1.3 Environmental effects of leachate
Common environmental effects from landfill leachate are saprobibation, eutrophication and toxic effects.
Saprobibation
Large organic loads can make bacteria and fungi grow in large numbers which will consume the oxygen in the water. Such growth can be seen as white or grey mats in the bottom of a watercourse. Reduced level of oxy-gen deteriorates the living conditions, and the natural distribution of for example bottom animals and fish can be disturbed. Saprobibation can be addressed by setting emission limits of organic matter, or maximum al-lowed levels of oxygen depletion in the recipient.
Organic matter is usually analyzed as total organic carbon (TOC), chemical oxygen demand (COD), biochemical oxygen demand (BOD), either on filtrated or undisturbed water samples.
However most of the organic carbon in a treated (aerated) leachate are thought to be humic and fulvic acids. Fulvic acids consist of large mole-cules that have low biodegradability and thus low impact on the oxygen consumption.
Eutrophication
Leachate may have high concentrations of P, N and Na, Ca, K, Mg, Mn. Excess plant nutrients, mainly phosphorus and nitrogen, lead to eutrophi-cation which is algae blooms and the presence of nutrient demanding species. Some blue green algae produce toxins.
Ecotoxicological effects
Some substances are harmful to water-living organisms and can cause ecotoxicological effects. These substances can be organic or inorganic, natural or anthropogenic. The most harmful substances are toxic, slowly degrading and bio accumulating. Degrading substances can also cause effects, especially from long-term exposures, but with limited impact. The toxicological effects from leachate can to some degree, be evaluated from chemical analyses of known toxicants. A lot of substances are listed with data on degradation (hydrolysis, photo degradation, soil, air and water half lives), potential bioaccumulation and toxicity towards different species (algae, bacteria and other). Leachate will, however, contain a large number of unknown substances necessitating toxicity tests in addi-tion to chemical analyses. Such tests measure, to a variable extent, the accumulated toxicity in the leachate.
Biological investigations in receiving waters can reveal ecotoxicologi-cal effect such as redistributed or missing species downstream of a leachate emission point. If the leachate also contains high concentrations of organic matter and nutrients, the saprogenic effects and eutrophication
can mask toxicological effects. The most pronounced masking effect in leachate is due to ammonia toxicity, especially at high pH.
Besides acute toxicity, long-term or chronic effects have to be consid-ered. Recently such effects, linked to reproduction and development in animals through hormonal activity, have received increased attention. Release of substances into the aquatic environment through municipal and industrial discharges has been shown to interfere with hormone di-rected processes in the organisms. Some circumstantial evidence has been presented that substances from landfill leachates may cause impaired reproduction in some fish species (Linderoth et al. 2000, Noaksson et al. 2001, 2003). Both estrogenic and androgenic hormonal effects have been detected by in vitro testing in landfill leachates (Svenson et al. 2004 a,b). According to Svenska renhållningsverksföreningen (2003) the crustacean Nitocra spinipes are recommended for testing ecotoxicological effects from leachate, because it has sexual reproduction, has a short and well defined life cycle and lives in salty or brackish waters.
Hormone disrupting effects from landfill leachates
Landfill leachates contain substances that affect the hormone regulation if exposed to higher aquatic animals, such as fish and amphibians. Sub-stances identified so far have been the natural and synthetic steroids es-tradiol and ethinyleses-tradiol, and the industrial chemical bisphenol A, which are known to interfere with the estrogen receptor (Svenson et al. 2004b). The chemical identity of substances causing androgenic effects is not known. Their composition is heterogeneous and their water-solubility properties vary (Svenson et al. 2004a).
Estrogens and androgens can be found in leachates. If the hormones are released into waters, they may affect aquatic organisms. Similar lev-els to those detected in leachates have also been recorded in treated mu-nicipal wastewaters. The effects of wastewater treatments on the hormone disrupting effects in landfill leachates have been studied (Ek et al. 2003). There are methods capable of reducing the hormonal reducing effects in landfill leachates.
1.4 Degree of stabilisation/maturation
(Final Storage Quality)
The waste degradation processes in a landfill goes through a number of phases, see Figures 1 & 2. The gas phase emission goes from “normal” air quality to intermediate phases where CH4 and CO2-concentrations increase. Closer to the maturation of the waste, the landfill air quality returns to its initial quality with high concentrations of nitrogen and low concentrations of CH4 and CO2. According to this, a landfill can be con-sidered to be stable when these gases in intermediate phases, are strongly
Handling and assessment of leachates from municipal solid waste landfills 23
reduced after relatively high levels (50–60%), assuming that other factors are not limiting. This is reflected in recommendations from the UK where there are limit values for diffuse emissions of methane equal to 1*10-3 mg/m2*s, equivalent to 0.004 m3 methane per tonne per year for a 10 m deep landfill (Knox, 2004).
The processes reducing the concentrations of organic and inorganic substances in the leachate phase with time are more complex than for gases, since several of the reduction rates level out for long periods of time, e.g. for NH4, Cl and COD, see Figure 2. For a number of organic and inorganic parameters a late release from a landfill cannot be ruled out, e.g. for heavy metals (see Figure 2).
Figure 2. Distribution of landfill leachate concentrations with time (Christensen & Kjeld-sen, 1995)
The definition of final storage quality (FSQ) has implications for the op-eration and management of a landfill site, both during its opop-eration and after its closure. FSQ is generally defined as the state of the landfilled waste at the time when the emissions become and remain acceptable, and active environmental protection systems become unnecessary (Hjelmer et al., 2004). FSQ might be technically defined in different ways, either as a flux or as concentrations of contaminants, the first being more achievable within a reasonable timeframe, and the latter being easier to control. It is generally believed that FSQ is not possible to reach in a reasonable time-frame unless the waste is treated prior to or during landfilling.
Residual material from the degradation of organic waste can be de-fined as stable or mature. A stable material consumes little oxygen in an aerobic process, has a high C/N-ratio (see Table 2), and a specific micro-bial flora characterised by moderate temperatures (20 ºC), such as actin-omycetes and other soil micro organisms. A mature material can be de-scribed as a material not being anti germinating (except for possible high levels of salts), and having a low content of fatty acids, a high content of humic acids, and a mineralized nitrogen consisting of mainly of nitrate and not ammonium.
Table 2. Examples of organic matter and nitrogen in waste and leachate (Norway).
Landfill 1 * Landfill 2 Mean landfills Landfill3 Biocell
Leachate Waste
KOF mg/l 138 264
TOC mg/l 46 88 85
Tot-N mg/l 7,5 8,3 100
C/N - 6,1 10,6 0,85 3 16
* Landfill 1 & 2: leachate from old landfills (closed > 30 years ago). Mean landfills = mean value Norwegian leachate 1998-2002. Landfill 3 = excavated and sieved MSW from an active landfill. Biocell = excavated from household organic waste biocell.
Handling and assessment of leachates from municipal solid waste landfills 25
According to Heyer & Stegmann (1997) a model estimate of BOD half-life is 6 years during anaerobic degradation of organic matter in condi-tions with 30ºC. This half-life can be tripled with a temperature reduction to 10 º C (Nielsen & Petersen, 2000), see Figure 3 and Table 3. The fatty acids will, measured as BOD, be consumed during the active period of the landfill. Under warm conditions, an 85% reduction of organic matter requires less than 20 years. In cold climates, e.g. in the Nordic countries, this process takes more than 50 years.
Table 3. Estimate of time periods to reach limit concentrations (after Heyer & Stegmann, 1997)
Parameter* Limiting C mg/l Concentration at the beginning mg/l Half-life Years
Period to limit value Years COD 200 (Germany) 60 (Switz.) 2000–43 000 25–96 120–220 200–300 TKN 70 (Ger.) 5 (Switz.) 800–3900 40–150 120–300 280–580 Cl 100 500–4200 40–90 120–220
*TKN=Total kjeldahl nitrogen
A similar reduction can be observed for VOC in the gas from composting (Figure 4), with a half-life of ca. 23 days, equivalent to 47% of the total degradation period (Bergersen & Berg, 2001). The total annual VOC emissions from incineration in Norway are estimated to 300 tons (Wei-demann, 1997). Composting plants have different control measurements, usually for temperature, O2 and CO2, more seldom CH4, VOC and others (Østdahl & Tronstad, 1995). The operation of a landfill is, however, dif-ferent from operating a compost or digestion plant, with significantly less operational control.
Figure 3. Model reduction of VOC under 30 ºC (diamonds) and 10 ºC (circles). 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 Time (years) R e s idue or ga n ic m a tte r
Based on leaching tests in landfill simulators the half-lives and the corre-sponding times for achieving specified concentration limits in leachate have been calculated according to the equation below, see Table 3 (Heyer & Stegmann, 1997):
Ct = Co * e –k(t-To)
Ct is concentration at time t Co is start concentration k = half life constant t= test period (days)
To=start of leachate recirculation in test (days)
Figure 4. Measured reduction of VOC during composting (Bergersen & Berg, 2001). A number of parameters and factors are listed below. These can be used to evaluate the FSQ. The parameters are not in a priority sequence. Their suitability will vary depending on local site specific conditions.
Leachate is found to contain substances represented in all the waste that is landfilled. Landfill gas on the other hand, can vary more. For ex-ample, typical municipal and organic waste have gas potentials of 150– 300 litre/kg DM, while typical extraction rates of landfill gas are 30–50 litre/kg DM, thus only representing a small fraction of the gas produced.
Measuring biological degradability of solid waste samples also raises many methodological and statistical questions. Also, waste and landfill types vary, e.g. monolandfills to municipal waste landfills. Another prob-lem might be the evaluation of potential emissions based on “harmless” factors such as residual COD.
Suggested parameters for evaluating final storage quality (FSQ):
0 200 400 600 800 1000 1200 0 2 4 6 8 10 12
Compost age (weeks)
VO C ( pp m )
Handling and assessment of leachates from municipal solid waste landfills 27
Leachate specific parameters
• Comparisons with landfill acceptance criteria (i.e. leaching criteria for inert waste, for example Co=160 mg/l for DOC, see Council decision 2002 of the Waste Directive 1999/31/EC, Annex G.3). Comment: These are criteria for receiving waste to final treatment and are not necessary suitable for leachate emissions
• Specific limit values (COD<200 mg/l, TKN<70 mg/l Germany; COD<60 mg/l, TKN<5 mg/l, Cl<100 mg/l Switzerland)
• Low BOD/COD ratio (<0.1 – 0.2)
• High ratio of non-degradable/degradable organic matter (i.e. humic acid*/BOD-ratio)
• High C/N ratio
• High NO3-concentrations • No volatile organic acids(*)
• Occurrence of (specific) humic acids*
• Occurrence and disappearance of a secondary release of pollutants, for example selected heavy metals*
Gas specific parameters
• CO2 <1.5% and CH4<1 % for at least 2 years (UK), or
• CO2< 22 l/hour and CH4<15 l/hour from any borehole for > 2 years (UK).
• CH4<25 m3
/hour as total from landfill, or • CH4<5 m3
/hour and hectare (DK).
• Comment: this might be a “strict” criteria, see e.g. Table 5.
• VOC in the gas* Comment: VOC in landfill gas from active sites vary from 2–22 ppm (Haarstad & Bergersen, 204; Bergersen & Bøen, 2004)
• Other waste gases (e.g. H2S, CO)*
Waste specific parameters:
• Measurable degradable materials (cellulose, hemicelluloses, or acid digestible materials)*
• “Indirect” measurements such as loss on ignition (LOI), COD, TOC, BMP, aerobic oxygen consumption (AT), and others. Comment: the degradation of individual substances is generally of less importance than the overall degradability measured by indirect measurements • Biological methane potential (BMP)<0.1 m3
methane per dry tonne (or > 99.9% degradation)
• Directive for bio waste (proposal) AT4<10 mg O/g dry matter (DM) • Compare with Directive for bio waste (proposal) <30 Nm3
gas /t dm or ~ 85% degradation
• Guidelines for mechanical biological pre-treatment (MBP) from Austria: sum gas generation GS4<20 Nm3/t DM, AT4<7 mg O2/g dry matter (DM); from Germany: AT4<5 mg O2/g DM or biogas potential over 21 days, GB21<20 Nl/g DM
• Presence of microbial flora typical of low-temperature (<20 ºC); micro organism typical for soil or actinomycetes typical for aerobic
conditions dominate over typical waste degradation micro organisms such as methanogens, acetogenic and sulphate reducing bacteria * Parameters and factors with few data and experience
2. Sampling
Guidelines/Programmes
2.1 Denmark
The Guidelines on Landfilling (Miljøstyrelsen, 1997) provide some guid-ance to be used as a starting point when setting up a leachate monitoring programme for landfills for inert waste, mineral waste and non-hazardous, mixed waste, respectively. They are presented in Table 4. Table 4. Proposed analytical programme for monitoring of
leachate from Danish landfills (Miljøstyrelsen, 1997).
Unit for inert waste* Unit for mineral waste Unit for non-haz. mixed waste Parameter
Extended Routine Extended Routine Extended Routine
pH P P P P P P Conductivity P, M P, M P, M P, M P, M P, M TDS P P P, T P, T P, T P, T BOD5 P,T NVOC/DOC P, M P, M, T P, M, T P, M, T AOX P, M, T P, M, T P, M, T GC-FID screening P,M Total N P P, T P, T Ammonia N T, M T, M Chloride P, M P, M P, M, T P, M, T P, M, T P, M, T Sulphate P, M P, M P, M P, M P, M Sulphide P P, T P, T P, T P, T Na P, M P, M P, M K P, M, T Ca P, M P, M P, M Fe P, M P, M Cd P, M P, M Cr (total) P, M P, M Cu P, M P, M Ni P, M P, M Pb P, M P, M Zn P, M P, M
P: Parameter related to the general pollution potential of the landfill M: Parameter related to the monitoring of groundwater and surface water T: Parameter related to the treatment of leachate
*: At inert landfills where leachate collection is possible
The Guideline states that the leachate monitoring programme for a spe-cific landfill does not necessarily need to include all the parameters listed in Table 4 and that, on the other hand, it may be necessary in specific cases to add further parameters that are not listed in the table. Table 4 indicates the choice of parameters. It shows whether they were chosen to provide information in relation to the general pollution potential of the landfill (P), the groundwater or surface water monitoring programme (M)
or the loading or influence on the leachate treatment system (T). The Guideline also states that the leachate should be analysed for all parame-ters that occur in the groundwater/surface water monitoring programme. New Guidelines will be released once the Council Decision has been implemented into national legislation.
It seems reasonable to assume that future leachate monitoring pro-grammes will include analyses of the parameters for which leaching limit values have been set in the acceptance criteria of Council Decision 2003/33/EC and the national implementations. The DEPA intends to add leaching criteria for some organic substances or groups of organic sub-stances to the list of leaching limit values for inorganic parameters (and DOC/phenols) given in the Decision. These organic parameters (such as BTEX, PAH, PCB and mineral oil) are therefore likely to become a part of the standard analytical programme for future leachate monitoring schemes at Danish landfills, at least for the extended analysis version.
Annex A.1. includes a listing of maximum concentrations in ground-water as a basis for a risk assessment of leachate emissions to groundwa-ter.
2.2 Finland
The monitoring requirements for the groundwater in Finland are:
• The monitoring program for specific locations shall follow the general and specific specifications given in the relevant directives and country specific regulations (§§14 and 15. and appendices I & III)
• Monitoring of groundwater must include at least two monitoring points in the groundwater outflow region and at least one monitoring point in the groundwater inflow region
• Groundwater wells utilised for drinking water purposes have to be monitored
• The water level inside the waste filling has to be monitored every six months. The groundwater level has to be monitored every sixth months. If the groundwater level varies, the monitoring level has to be increased.
• The sampling frequency and the analysed substances are determined site specifically. In addition, the velocity of the groundwater flow has to be taken into account. The measurements should provide
information on water quality changes.
• If the quality of the groundwater is found to be deteriorated or permit levels are exceeded, the instruction in the permit should be followed. • The measurements and the quality data has to be collected, registered
and presented in the form of table that allows easy detection of any changes in the water quality
Handling and assessment of leachates from municipal solid waste landfills 31
The monitoring requirements for the surface water in Finland are: • At least two monitoring points are selected, one in the inflow region
of the landfill and one in the outflow region of the landfill. These points are monitored for the quantity and quality of the water four times a year and after the closure of the landfill twice a year. The monitoring requirements for the leachate in Finland are:
• The quantity and quality of the leachate has to be monitored at every discharge point of the leachate.
• The leachate conducted to the treatment has to be monitored so that the effectiveness of the treatment and the pollution discharge of the landfill can be evaluated
• The quantity and the electrical conductivity have to be measured every week except during the peak discharge every day.
The other quality parameters are analysed every three months. During the after-care phase of a landfill the parameters are monitored every six months. The quality parameters included in the analysis program are de-termined by the quality of the waste
In practice, the monitoring points of the groundwater have been more than minimum three points in almost every case. The leachate monitoring contains normally more substance analysis than other monitoring and is utilised for the evaluation of the possible pollution discharge to the groundwater and the surface water.
It is a general requirement that both the quantity and quality of the leachate are measured. Also the sediment in the leachate should be ana-lysed in order to measure substances with low water solubility.
2.3 Iceland
Landfills are categorized according to capacity and type as following: • Cat. 1: landfills for non-hazardous waste, capacity > 5000 tonnes a
year (4 total)
• Cat. 2: landfills for non-hazardous waste, cap. 500–5000 tonnes a year (7 total)
• Cat. 3: landfills for non-hazardous waste, cap < 500 tonnes a year, and also landfills for inert waste with a capacity of > 20,000 tonnes a year (17 total)
Standard parameters that have to be monitored at all landfills in category 1–3 are typically COD, NH4+/NH3, conductivity, pH and temperature. Furthermore, the range of pollutants/parameters to be monitored and fre-quency of leachate sampling is related to capacity of the landfill as shown below.
Table 5. Monitoring programme for Icelandic landfills, Cat. 1–4
Category Parameters to be monitored Frequency Type of sample
1 pH, conductivity, temperature, COD, NH4+/NH3
2 times a year Leachate before & after treatment* and/or in bore-holes up- and downstream of landfill
Leachate flow weekly Leachate before & after treatment* and/or in bore-holes up- and downstream of landfill
NO3-, total-N, total-P, Pb, Hg, Cd,
AOX, oil/fat
Once a year Leachate before & after treatment* and/or in bore-holes up- and downstream of landfill
Fe, Cr, Cu, Zn, As, Ni Once every 3–4 years Leachate before & after treatment* and/or in bore-holes up- and downstream of landfill
Pb,Cd,Hg,AOX Once every 4 years In mussels and sediment near outlet
Groundwater level In boreholes near landfill
2 pH, conductivity, temperature, COD, NH4+/NH3
Once every 2 years Leachate before & after treatment* and/or in bore-holes up- and downstream of landfill
Groundwater level 4 times a year Leachate before & after treatment* and/or in bore-holes up- and downstream of landfill
Other parameters In case of high levels in standard package
Leachate before & after treatment* and/or in bore-holes up- and downstream of landfill
3 pH, conductivity, temperature,, COD, NH4+/NH3
2 times a year Measured in recipient**
Pb,Hg,Cd,AOX NO3-, total-N, total-P,
oil/fat
In case of high levels of standard package
Measured in recipient**
Groundwater level 4 times a year In boreholes near landfill 4 pH, conductivity, temperature,,
COD, NH4+/NH3
Once a year Measured in recipient**
Pb,Hg,Cd,AOX NO3-, total-N, total-P,
oil/fat
In case of high levels of standard monitoring
Measured in recipient**
Groundwater level Four times a year In boreholes near landfill * Treatment options used in Iceland: fat/oil separator, sand or peat filter, oxidising pond
** Leachate collection and treatment not obligatory if values within the limits of the permit. Recipient can both be surface- and groundwater
In one case (Álfsnes, Sorpa, Reykjavík, capacity over 100.000 tonnes a year, Iceland´s largest landfill for municipal waste) monitoring of the sediment as well as mussels in the neighbourhood of the leachate outlet (sea) has to be monitored once every 4 years. On another landfill, Kirk-juferjuhjáleiga in South-Iceland, sediment in the recipient (river Ölfusá) is monitored on a every fourth year.
Handling and assessment of leachates from municipal solid waste landfills 33
Where leachate is collected, also leachate flow in the outlet to the re-cipient has to be monitored on a weekly basis, but there are only a few landfills operating such a system today (has to be in place by 2009 under the LFD.
In Table 5, leachate data from respectively category 1 and category 2 landfills are brought together for the period 1998–2004. These are the most recent and accurate data available in Iceland today. These values are based on samples taken after treatment of the leachate, i.e. as it enters the recipient. (Leachate collection and treatment is not carried out with land-fill-categories 3 & 4 in Iceland and therefore monitoring programs there are based on quality control of the ground- and surface water near the landfill).
2.4 Norway
The waste hierarchy in Norway aims to minimize the generation of waste, and to ensure the best management of the waste generated. Also, regula-tions are implemented to protect the environment from emissions from landfills. The recipients must be protected, preferably according to the guidelines TA-1467 and TA-1468.
The two most relevant guidelines regulating landfills and leachate are: • Guidelines on environmental risk assessments on landfill bottom
liners and leachate collection, TA-1995/2003, issued in 2003. It seeks to control diffuse pollution from landfills. The guidelines for
environmental risk assessment prescribe a three level investigation of landfills. The evaluation is based on three steps:
a) Source characterization – leachate and waste
b) Transport characterization – establish a water balance for the landfill and the local dissemination of leachate to the
environment
c) Recipient characterization – establish a model of the diffusion of leachate into recipients and verifying effects
• Guidelines on monitoring of leachate from landfills, TA-2077/2005, issued in 2005. This regulates the controlled emissions of leachate from landfills.
The guidelines include a sampling programme with 13 general parame-ters (of which 3 with defined thresholds), 13 metals and elements (of which 10 with defined thresholds), 12 organic pollutants (groups) (of which 7 with defined thresholds), and 4 toxicological (3 when leachate is going to a wastewater treatment plant), see Annex D.5. In addition there are 28 parameters in leachate sediments (of which 19 with defined
thresholds). 23 substances listed in the guidelines are also listed in the Pollution Inventory (Robinson & Knox, 2003).
Guidelines on landfill leachate monitoring include an annual sampling programme with 24 parameters, of which 10 are general, 10 are metals and 4 are organic pollutants (groups), see Annex D.4. In addition, there are 16 parameters for leachate sediments, 3 general, 10 metals and 3 or-ganic pollutants. There is also a sampling programme with 5 year inter-vals, consisting of 14 organic pollutants (group), 3 toxicity and 15 pa-rameters for leachate sediments.
A summary of the guidelines and parameters included in them are given in the Appendices.
2.5 Sweden
The Swedish guidelines give recommendations on the design of a moni-toring programme for leachate, surface water, sediments and groundwa-ter. Specifically, there are recommendations on suggested parameters, sampling methods, sampling frequency and data reporting. A description on how to carry out hydrological evaluations is also included.
The monitoring programmes are usually separated into phases, e.g. a basic and an extended phase, screening etc.
Common reporting practices are to evaluate total emissions of organic matter, nutrients and toxicants relative to emission limits that are recipi-ent independrecipi-ent. Another phase can be recipirecipi-ent specific investigations considering local conditions such as e.g. dilution. The plume of sub-stances is evaluated relative to acceptable influential areas beyond which no negative effects are accepted.
2.6 Examples of leachate reporting in some EU countries
In the UK emissions are monitored and reported through the landfill leachate Pollution Inventory reporting tool (Robinson & Knox, 2003). The Pollution Inventory (PI) for England and Wales requires operators at up to 1000 landfill sites to report their annual emission load of PI sub-stances in leachate, for the first time in 2003. The subsub-stances are listed in the table in Annex G.1. Each substance is listed with a reporting thresh-old value, given as annual mass flow. The reporting is carried out at 3 levels; NA (not applicable), when there are no emissions, BRT (below reporting threshold), and Emission.• In Germany leachate emissions are controlled through limit levels of 17 parameters, see Annex G.2.
Handling and assessment of leachates from municipal solid waste landfills 35
2.7 Differences in limit values
There are a number of limit values both for leachate emissions and for maximum concentrations allowed in the recipient (groundwater) in use in the Nordic countries and in the EU, see Table 6.
Table 6. Comparison of limit values
DK* N** D*** EU1**** EU2*****
General parameters (mg/l)
Cl 150 460 46 000
Sulphate 250 1500
NVOC 3 5a 200 k 160 h 1160 a
Tot N ( – nitrate) 1 + background 0.5 b 70 1160 b
NH4 0.5 + background
Tot-P 0.16 3
Metals and elements (μg/l)
Fe 200 As 8 2 100 60 0.13 Ba 4000 Pb 10 1.9 0.5 Cd 2 0.2 100 20 0.02 Cr 25 6.3 500 100 0.5 Cr VI 1 100 Cu 100 2.3 500 600 0.5 Hg 0.01 50 2 3.0 Mo 20 200 Mn 0.1 Ni 10 5 1000 120 0.5 Zn 100 35 1200 0.5 Organic pollutants (μg/l) AOX 500 0.02 Chlorinated solvents 1 50 c 0.02 Chlorinated benzene 10 DEHP 1 0.02 1,2-dibrommethane 0.01 0.02 i PAH 0.2 0.11 MTBE 5 0.02 Hydrocarbons, total 9 10000 Pentachlorphenol <detectable 1 d 1.2 Pesticides Total Single Chlorinated 0.5 0.1 0.03 0.5 e 0.01 j Phenoles 0.5 0.3 f PAH 2 0.11 Tin organic 0.01 0.11 Vinylchloride 0.2
* DK=maximum allowed concentrations in groundwater. Based on risk assessment, http://www.retsinfo.dk/ ** N=environmental risk assessment threshold values for diffuse emissions. *** Requirements for leachate emissions in Germany (Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, Germany, 2004). **** Council Decision 2003/33/EC limit values from percolation test defining inert waste.*****Pollution Inventory leachate reporting values assuming average Q=118 m3/d (Robinson & Knox, 2003) a as TOC bas Tot-N cvolatile chlorinated
hydro-carbons dchlorinated phenols ephenoxy acids fphenol index hDOC i as PBDE jas aldrin kas COD
The Danish limit values refer to concentrations in groundwater to evalu-ate the environmental risk; the Norwegian threshold values refer to leachate (and leachate sediment) samples as diffuse emissions, also as guidance to evaluate the environmental risk; the German limits refer to leachate samples; the limits in the EU directive are to be used on percola-tion tests limits for inert waste, and the Pollupercola-tion Inventory are generally
for all (industrial) emissions, where an equivalent leachate volume has to be defined in order to calculate emission concentrations. It is clear that the EU1 limits are, as can be expected, high, but also the German limits are systematically high. Also, the German limits and the EU1 in practice almost set no limits for organic pollutants. The Pollution Inventory has, assuming a certain leachate discharge, high limits for general parameters, and very low limits for heavy metals and organic pollutants.
3. Existing Leachate Data –
National Levels
The leachate data reported here are not necessarily collected according to the guidelines listed in the previous chapter.
3.1 Denmark
There is no central collection and management of landfill leachate moni-toring data on a national level in Denmark. Each of the 13 Danish coun-ties manages its own leachate monitoring data. In many cases, the data are merely stored as raw data. To collect and organise the leachate moni-toring data from all the Danish counties and make them compatible and suitable for statistical analysis is a major undertaking, which goes beyond the scope of this project. Instead, we have chosen to organise and present a time series of leachate quality data from a limited number of selected landfills. In this way, the data can be related to specific categories of landfills and to the age of the landfill (in one case for mineral waste to the liquid-to-solid (L/S) ratio). A listing of leachate monitoring is given in Annex A.1.
A few comments on the landfill cells at Ganløse, Denmark
Cells 1 and 2 were established in 1979 and closed and covered with a clay and topsoil cover in 1983/84. The cells contain the following waste: Bottom ash, fly ash and scrap metal from a MSW incinerator 82,000 m3
Refuse from a container site and recycling station 11,000 m3
Wastewater treatment sludge 7,000 m3
Household waste (placed during the first half year due to an emergency) 41,000 m3
Leachate has been collected throughout the lifetime of the landfill cells. Cell 3 was established in 1983. It was filled up and covered with a clay and topsoil cover by the end of 1986. It is also a mineral waste landfill, and contains mostly MSW incinerator bottom ash, fly ash and scrap metal.
Leachate has been collected throughout the lifetime of the landfill cell, but only data from 1990 and onwards are included in this study. BOD and COD are reduced to 1% and 5% of the initial concentrations in 24 years, respectively, and Tot-N to 35% in 18 years.
3.2 Finland
In Finland, there are no specific targets on environmental quality stan-dards for leachate that is transported to municipal waste water treatment plants. The effect of the leachate on municipal waste water treatment is normally estimated by comparing the quantity of the effluent on the quan-tity of the municipal waste water and the concentrations of BOD, COD, ammonia and metals. Toxicity tests may be utilised also for assessment of the treatment (Marttinen et al., 2000). The municipal waste water treat-ment in Finland is mostly based on biologically activated sludge (ammo-nia, BOD) and chemical precipitation (phosphorus).
The leachate is a mixture of thousands of dissolved and solid sub-stances. The concentrations and compositions of substances present in the leachate are changing due to the biological, chemical and physical proc-esses in the landfill. It is possible to divide the development of the landfill maturing in five phases, which describe the development of the biological processes in the waste filling in time (Marttinen et al., 2000):
Phase 1. Aerobic phase Phase 2. Transitional phase Phase 3. Anaerobic acid phase Phase 4. Methane production
Phase 5. Humic phase or developed phase
The quality of the leachate and the landfill gases is different in each phase. For example, the COD, volatile fatty acids and heavy metal con-centration in the leachate are at their highest and the pH in the lowest in the anaerobic phase. The COD/BOD relation in the leachate reveals the age of the waste filling in the landfill. The higher the relation, the older the landfill is. Ammonium, nitrogen, phosphorus and chloride concentra-tions are not dependent on the aging stage of the waste filling. So-called typical landfill leachate with regard to substance concentrations is impos-sible to define (Marttinen et al., 2000; Whalström et al., 2004).
Data of leachate quality reviewed in a study in 2001 is collected in ta-ble B.1.1. Here, data from 45 closed municipal waste landfills established before 1987 is collected in addition to data from two municipal waste landfills established after 1987 (Marttinen et al., 2000).
Annex B.1.2. shows leachate quality data from six landfills. These data are on quality of percolated water in the landfill and on quality of the water in the surrounding ditches. The leachate of the landfill normally includes other water from the landfill area (Kettunen et al. 2001).
Handling and assessment of leachates from municipal solid waste landfills 39
The general conclusion from this study was (Kettunen et al. 2001): • The water samples were diluted compared to the results in other
European countries
• The leachate total organic carbon and chemical oxygen demand are at the same level as in the municipal waste water
• The nitrate concentrations were high compared to municipal sewage except in one landfill
• The chloride concentration is high enough to cause corrosion • Manganese and iron concentrations were high
• Heavy metal concentrations (chrome, copper, nickel) were most of the time below detection limit (0.1 mg/l)
• The concentrations vary depending on the season
• The concentrations in the waste filling were higher than in the leachate collected at the collector basin (2–4 times higher)
• The concentrations in the ditch-water were in two of the cases higher and in one case lower than the quality of the leachate. This was probably due to dilution of leachate by other water in the landfill area. In another study, samples from 60 municipal waste and industrial waste landfills were analysed for heavy metal and other chemical element con-centrations in the leachate. It was concluded that these concon-centrations were low (Al, As, B, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn, Ca, Fe, K, Na, P, S) (Marttinen et al., 2000).
Also, 42 different organic substances were analysed in five landfills (Kettunen et al. 2001). The substances are known to be toxic for health or environment. None of the substances were detected in two of the land-fills. In the rest, only some substances exceeded the detection limits. The highest concentrations and more frequent substances found in the leachate were PAH substances (at most 10 times the target value set for drinking water) and phthalates.
Organic substances have been tested in at least 60 landfills, and the concentrations are found to be low (Marttinen et al., 2000).
3.2.1 Toxicity
There were carried out toxicity tests of the leachate in six municipal land-fills. (Kettunen et al. 2001). The toxicity was tested with Daphnia and Raphidocelis subcapitata. It was concluded that the leachate was toxic to Daphnia in concentrations 18–48 % (LC50). If the leachate is diluted to 1/2 – 1/5 parts, it would not be toxic to water fleas. The toxicity was re-markably reduced in almost all leachate treatment plants (Kysely, 2002).
Results from inhibition tests with algae shows a toxicity of leachate at concentrations of 7–24 % (EC50). This means that alga growth was de-creased by 50 % at concentrations of 7–24% of leachate. The toxicity was
significantly decreased in the treated leachate water. However, in one test of landfill leachate mixed with treated municipal wastewater, the effluent was toxic to algae but not to water fleas. This may be due to ammonia and iron present in the effluent. If the leachate was diluted from 1/20 to 1/100 it was not toxic but increased the growth rate of algae and thus increased the eutrophication in the receiving waters. The leachate pH was adjusted to 7.0 and solids were filtered out before testing. The test was thus testing diluted and biologically available substances (Kettunen et al. 2001).
In Finland the treatment was concluded to be important for organic compounds (COD, BOD7, and TOC) and ammonia because of their sig-nificant concentrations in the leachate. In addition, all investigated leachates were toxic in water environment. However, the phosphorus and heavy metal concentrations were low except for iron and manganese. PAH substance, phthalate, phenol and cresol concentrations were highest of all the tested 42 organic substances, but in general all organic sub-stance concentrations were low.
The leachate will become concentrated as the landfill structures are improved, i.e. the geological barriers, bottom liners and other structures required in the Directive of Landfills are built.
3.3 Iceland
There were approximately 30 operational landfills for municipal waste in Iceland in 2002. It is expected that the number of operational landfills will drop substantially after all the provisions of the Landfill Directive have come into force (2009). All operators of landfills had to send in an adaptation plan before 31 December 2003. Landfills not meeting the cri-teria of the Landfill directive have to be closed by no later than 16 July 2009.
Time series of leachate monitoring exist for most landfills in Iceland. However, the range and frequency of samples are a.o. dependent on the capacity and type of the landfill. In Iceland there are only landfills for non-hazardous waste from households, smaller companies, building and demolition waste (B&D), slaughterhouse waste etc., and inert waste e.g. soil, concrete, glass, stones etc. On many landfills for inert waste there is also a special area where garden waste, used in composting is stored. There are currently no landfills for hazardous waste in Iceland, but one such landfill is in preparation (including contaminated soil).
A summary of leachate monitoring from Iceland is given in Annex C.1.
Handling and assessment of leachates from municipal solid waste landfills 41
3.4 Norway
There were approximately 100 operational municipal waste landfills in 2002. A survey in 2004 showed that 39 landfills were applying for con-tinued operation. All landfills are supposed to operate according to The landfill directive since July 2005. By 2009 a total ban on the landfilling of organic waste is expected.
Investigations of reports to the county governors (Fylkesmannen) on regular annual leachate monitoring show that 65 parameters were ana-lysed in untreated leachate, see Annex D.1, Tables D.1.1. to D.1.5. The data apply to the period from 1998 to 2002 and were added to a leachate database (DISIG, Haarstad et al., 2003). The values are averages of the annual mean for each location, eliminating differences in sampling fre-quency using the method of bias corrected means (Parking & Robinson, 1993).
The number of landfills reporting data was 51 up to 2004. These are mostly landfills for ordinary household waste, although waste characteris-tics are assumed to change over time due to changes in regulations and other factors, particularly after 2009 when landfilling of degradable or-ganic waste will be banned.
The guidelines for leachate monitoring were published in 2005 by SFT, and are separated into an annual and a 5 year programme. The leachate quality and quantity is the basis for estimating the emissions that are evaluated against the environmental conditions in the recipient. Up to now the emissions have been evaluated against treatment target values, typically 50–75 % removal of COD, 30–50 % N, and 70–80 % Fe.
In Norway leachate quantities varied between 5 to >1023 m3/day, with a mean value of 118 m3/day. A previous study estimated the leachate quantity to 300 mm to 600 mm (Haarstad, Mæhlum & Kraft, 1998).
Table 7. Comparison of leachate and wastewater concentrations for selected parameters*
Parameter Leachate Leachate mean Wastewater Wastewater mean General parameters (mg/l) COD 18–5028 430 200–600 77 BOD 9–1600 157 180–300 324 Tot-N 4–449 100 12–100 66 NH4-N 7–685 96 54 Tot-P 0,2–75 2,5 10–25 15 Heavy metals (μg/l) As 0.65–163 8 Cd 0.025–95.8 1.2 0.29–0.76 0.51 Cr 1–645 20 2.7–9.2 7.3 Cu 1–1343 11 28–399 79 Hg 0.005–62 0.32 0.11–0.72 0.25 Ni 1–169 21 2.1–22.5 11.8 Pb 0.3–221 5.0 0.75–6.44 1.77 Zn 0.1–2163 101 20–195 84 Organic pollutants (μg/l) PCB 0.01–3.1 0 0.02–0.04
Chlorinated phenols 0.5–1 0.7 i.p.
Phthalates 0.01–250 3.64
PAH 0.08–23.8 2.70 0.03–5.0
* Midttun, 1997; Østeraas, 1987; Mosevoll et al., 1999.
Table 7 shows that leachate is generally more concentrated than ordinary wastewater, especially for COD and some heavy metals (Cd, Cr and Pb), both as mean (1 to 5 times) concentration but even more pronounced for maximum concentrations (up to > 10 times), mainly due to a more con-centrated flow. Leachate generally also contains more substances.
After implementation of the Landfill Directive, the government intro-duced a graduated pricing of landfilling based on the environmental status of the landfill and the quality of the bottom liner. By late 2004, environmental impact studies had been conducted at 39 landfills (Amundsen et al., 2004), see Tables D.1.6. to D.1.10. The diffuse emis-sions are evaluated against target values. If these values are not met, the quantity of the diffuse emission is evaluated, and also the possible effects in the recipient. Studies on diffuse emissions from landfills show that the threshold values are exceeded to a large degree when evaluated according to general parameters (8 to 286 times), less by heavy metals (2 to 80 times) and least by organic pollutants (1 to 10 times). In leachate sedi-ments the only parameters measured above the threshold limits were phe-nols, PAH and Tin organic compounds.
Time series of a) an active landfill and b) a closed landfill are pre-sented in Annex D, Figures D.1 to D.16.
Landfill a) was established in 1962, covers nearly 20 hectares, with a volume of 500 000 m3, and received about 52 000 tonnes per year, 90 % of which was residual waste from manufacturing, construction and trade (2002). In 1995 household waste constituted 30 % of the landfilled waste. The leachate samples are analysed 4 times per year.
Handling and assessment of leachates from municipal solid waste landfills 43
The COD has increased by a factor of 3 in 11 years, from approximately 1500 mg/l in 1993 to 4500 in 2004, but the values also show large sys-tematic variations.
The Tot-N increased by a factor of 2.7 in 15 years from 1989 to 2004. Cl and electrical conductivity show a weak decline indicating an in-creased hydraulic load through the landfill. Fe shows no systematic trend but seems to have systematic variations. pH is slowly increasing.
Landfill b) was established in 1962 and closed in 1997. It covers 6 hectares, with a volume of > 500 000 m3. At the beginning of the period household waste dominated. Towards the end 35% of the landfilled waste was household waste. Hazardous waste was deposited up to 1970.
The COD decreased to 27% of the initial concentrations in 8 years at the closed landfill, from approximately 330 mg/l in 1996 to 90 in 2004. The BOD decreased by 50% to 75 mg/l, and NH4-N to 40%. Also the electrical conductivity and Cl decreased to about 50% of the initial con-centrations.
Landfill gas has been measured in an old landfill closed in the 1960’s. The measurements were carried out in drill holes immediately after exca-vation. Table 8 shows that the gas concentrations are low for methane, CO2 and H2S, and approaching air quality for O2. (Snilsberg & Haarstad, 2004, 12/04, 26 s.)
Table 8. Gas concentrations in an old landfill
Gas Concentration (vol/vol)
CH4 1.3 – 11.8%
CO2 1.0 – 6.3%
O2 9.0 – 20.4%
H2S 0
CO 25 – 136 ppm
Extracts from waste from 2 old landfills had concentrations of BOD of 44 mg/l to 60 mg/l.
3.5 Sweden
Results from characterisation of untreated landfill leachates in Sweden are given in Annex E.1. Landfill leachates have been characterised with different levels of significance both in research projects and in control programs. In several research projects IVL has made chemical and bio-logical characterisation of municipal landfill leachates. Up to 400 pa-rameters have been analysed in grab samples from 30 sites. Both perco-late and ponds have been sampled. Samples from ponds are naturally more representative and less dependent on short-term variations e.g. in weather. The leachates in ponds are generally more diluted than the
